Mark uids holding WakeLocks as foreground

MMS and various other service that use internal message queues with
WakeLocks held were getting killed too soon, because the AM thought
they were done processing the request when they had only added it to
their internal queue.

This hack keeps processes belonging to uids with WakeLocks held in
the foreground.

It would be better to tie the WakeLocks to a specific process,
but the PowerManagerService does not seem to keep track of that
information.

Signed-off-by: Christopher Lais <chris+android@zenthought.org>